7/21/2019 The Physics of Sound - Joshua Kirby

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  he Physics Of Sound

The physics of sound is what this little article shall be covering as this is avery important area of sound design and music in a whole, this area is also

called “Acoustics” this small article should hopefully cover some of the factsyou didn’t (or needed to) know for whatever course, work or trial you may bedoing !et us begin

Envelopes

"irstly we shall discuss what a envelope is in terms of music, what one isused for and how it helps to make a song #ell, an envelope is used in music$uite a lot Attack, %ustain, &ecay, 'elease These for words make up themeaning of A%&', a set of letters very closely related to nvelopes as theyhelp make up the “shape” of the sound The envelope of an instrument is itscharacteristic relating to time and intensity, often called its shape, this is madeup by A%&', the attack is usually the large portion of the waveform, thehighest bit, then you have release which is when you release that note, thewaveform goes down into sustain where the note is still heard but is getting$uitter by the second and then we have decay where the note fades awaycompletely and can no longer be heard, that is the steps of A%&' #e cansee the envelope of instruments by looking at their waveforms as they makeup a shape or some description all the time

Beats

 Another terminology we use in music is beats eats mean many things, fore*ample, in film, a beat is the moment a characters emotion changes but wearen’t here for film, we are here for music, of course A beat in musical termsis, well, a beat, like a drum beat, it’s the rhythm essentially +t is the basic unitof time in a song and is used to keep a pulse going throughout the wholemelody Another way you can look at it is like a part of the song you tap yourfoot to or the things a musician counts when performing +f we look at beats,we need to look at downbeat, upbeat, off beat and on beat respectively eingdownbeat in a song is being the first beat in a bar, being upbeat is being thelast beat in that same bar and therefore anticipating the downbeat of the ne*t

bar, it’s a way to label the beginning and ending of a bar in theinstrumentation eing off beat in a bar means you are a weaker note, thesenotes being the second and fourth in a bar, or rather beats instead of notes,being on beat is being the first and third beat in a bar as these are usually theloudest and have the strongest accent in the melody and are the likeliestplaces for a chord change ff beat therefore focuses much more on thesyncopation of the weaker beats in a bar as opposed to the usual on beatones

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Phase

-hasing in music is very odd but very impressive at the same time if pulled off correctly asically, it’s when you have two instruments and you play the e*actsame thing on them in slightly different tempi, this basically makes a weird

effect where the melody will flip in and out of time with each other .sually atfirst there’s a small echo as they play slightly behind one another, then wehave a larger doubling effect because they are now playing e*actly in timebefore creating a confusing ringing sound due to sliding back into echo thendoubling and finally once more into unison

Harmonics

/armonics in music is where each sound in a se$uence of sounds has thebase fre$uency that is an integral multiple of the lowest base fre$uency Aharmonic can also be described as a single tone produced on a stringed

instrument by lightly touching an open or stopped vibrating string at a givenfraction of it’s length so that both segments vibrate, also called overtone orpartial tone